A recent study from Japan suggests that drinking three or more cups of green tea per day may help protect the brain from cognitive decline and dementia. The researchers analyzed data from over 8,000 volunteers aged 65 and older, who were observed for two years from 2016 to 2018, collecting information through food questionnaires and MRI brain scans. The study found an association between greater green tea consumption and smaller volumes of white matter lesions in the brain.
White matter lesions are structural changes that can indicate poorer brain health and are associated with cognitive decline, memory issues, and some forms of dementia, including vascular dementia and Alzheimer's disease. With age, these lesions often increase, raising the risk of dementia. Participants who drank at least three cups of green tea daily showed a decrease in white matter lesions compared to those consuming only one cup. Those who consumed seven to eight cups daily had even fewer white matter lesions.
The scientists measured total brain volume and characteristics of five brain regions using MRI scanning. However, green tea consumption did not appear to affect hippocampal volume or total brain volume. The hippocampus is associated with cognitive functions and memory, and its shrinkage can be a sign of cognitive decline and some kinds of dementia, including Alzheimer's disease. The researchers noted that drinking green tea had no effect on individuals with the APOE4 gene variant associated with Alzheimer's disease.
Variables such as age, gender, physical activity, and educational level were considered, and the correlation between green tea consumption and reduced white matter lesions remained even after adjusting for these factors. "Our results suggest that drinking green tea, especially three cups or more daily, may help in the prevention of dementia," wrote the researchers.
The reduction of white matter lesions could be explained by the effect of green tea on blood pressure and blood circulation, which may contribute to reduced dementia risk. Green tea contains catechins, antioxidant compounds with anti-inflammatory properties that help resist the accumulation of harmful mutations in cells. Catechins act directly on blood vessels and nerve cells, contributing to limit damage caused by oxidative stress. By lowering high blood pressure, green tea promotes better cerebral irrigation, thus limiting the risks of micro-lesions.
Japanese scientists found that among participants who drank 600 ml (approximately 20 ounces) of green tea per day, the volume of damage in the white matter was 3% less than among those who drank less than 200 ml. Participants who drank 50 ounces of green tea per day had white matter lesion volumes that were on average 6% lower than the low-intake group. Despite these findings, the study was observational, so the scientists could not prove that drinking green tea caused their study participants' brains to be healthier. "More prospective longitudinal studies and basic research are needed to validate our results," they stated.
The researchers noted that all participants in the study were Japanese, which implies certain genetic and lifestyle characteristics. They emphasized the need to carry out larger and longer studies, expanding research to more diverse populations to help validate these results and refine recommendations. They also observed that the benefits are mainly observed in individuals without major risk factors, such as depression or specific genetic predispositions.
Additionally, the researchers could not establish a connection regarding white matter lesions among coffee drinkers. While green tea showed an association with reduced white matter lesions, no similar effect was found for coffee consumption. This suggests the unique properties of green tea in relation to brain health.
White matter lesions often occur as we age and can be asymptomatic. However, when these lesions increase, the risk of dementia rises. The antioxidant and anti-inflammatory properties of green tea might protect blood vessels and promote brain health. This underscores the importance of a comprehensive approach to protect the brain, combining a balanced diet, regular physical activity, and appropriate medical follow-up.
This article was written in collaboration with generative AI company Alchemiq
